1. Field of the Invention
The present invention relates to a versatile office machine that uses a sheet feeder and, more specifically, to a device used by a facsimile device for accurately detecting the paper size of an original document.
2. Background Art
Office equipment that handles and copies documents, such as an electrophotographic apparatus or an image recording and forming device, must often determine the proper magnification of an original document to form a copy on a sheet of paper of a given size. In order to complete this process a versatile office machine must be able to determine the size of the original document. A document size detection device may include document guides, a guide gear, and document sensors for detecting the width of the original document. Such a document size detection device can detect four different document sizes.
In a facsimile device, however, the width of a recording sheet is specified at 216 mm (letter size) or 210 mm (A4 size). Thus, when a facsimile message is received that was created using an original document that was larger than the recording sheets used by the facsimile device, the facsimile device down scales the received facsimile message, or original image, to the specified size of the available recording sheets. The levels of magnification are shown in the following tables 1 and 2. Then the facsimile message is magnified to fit a recording sheet and the facsimile device forms the image onto a sheet of paper.
Many techniques that have been developed to determine the size of an original document are shown, for example, in U.S. Pat. No. 4,626,924 to Watanabe entitled Image Forming Apparatus, U.S. Pat. No. 4,698,511 to Sueda entitled Document Sheet Size or Position Recognition Device, U.S. Pat. No. 4,506,302 to Kurata entitled Cut Sheet Facsimile, U.S. Pat. No. 4,630,127 to Fuwa entitled Character and Picture Information Reading Apparatus, and U.S. Pat. No. 4,899,227 to Yamada entitled Image Processing Apparatus Detecting the Size or Position of an Information Portion of an Original. I believe it is possible to improve on the contemporary art by providing a document size detection device that avoids errors caused by excessive image size reduction, can classify the width of documents into a greater number of categories thus refining the accuracy of document width size detection, that avoids the loss of data due to using an improper reduction factor, that allows for a more precise degree of reduction to be used, and is economical to construct.